MWCNTs-solid phase extraction combined with ultra-high performance liquid chromatography-tandem mass spectrometry for the determination of eleven organophosphorus pesticides in river water.

A method for simultaneous determination of 11 organophosphorus pesticides residues in river water by MWCNTs-solid phase extraction combined with ultra-high performance liquid chromatography/tandem mass spectrometry was developed. After centrifugation and filtration, the target pesticides were enriched with MWCNTs-SPE cartridge. Then the pesticides adsorbed on MWCNTs were eluted with ethyl acetate and dichloromethane, the eluent was dried-up under nitrogen flow and the residue was dissolved in methanol-water (1:1, v/v) as sample solution. The separation was accomplished on a C18 column with the mobile phase consisting of methanol and 0.1% formic acid at 0.20 mL/min in gradient elution. The pesticides were detected in multiple reaction monitoring mode by a triple quadruple mass spectrometer. Good linearities were obtained within 1-200 ng/L, with the correlation coefficients greater than 0.998. The detection and quantification limits were in the ranges of 0.02-1.00 ng/L and 0.07-3.33 ng/L, respectively. The recoveries and relative standard deviations were in the range of 88.3-124.9% and 0.12-20.5%, respectively. The method has been successfully applied to the detection of 34 urban river water samples from Chengdu, China and 7 organophosphorus pesticides were detected with the concentrations of 0.32-211 ng/L. [ABSTRACT FROM AUTHOR]